Electric transformer



Jan. 13, 1931. MEYERHANS I 1,738,627 ELEcTnic TRAgSFORMER Filed June 12, 1929 F/g. at

/n venfor fiugusf' Meyer/vans- By I Patented Jan. 13, 1931 U IT1 J SW Aveusr MEYERHANS, or BADEN,ILSWITZERLA1:TD, ASSIGNOR T0 .axTIRNGRsnLLscHAFT .BR-OWN BOVER-I & 0111.; OF BADEm-sW-ITZERLAND, A Jom'nsTocK'coMrANY or v SWITZERLAND ELECTRIC TRANSFORMER Application filed j J'ime 12, 329, Serial No. 3 Zb, 1 7 5, and in Germany October 3 1,'1 9 28 I This invention relates to improvements in electric transformers and, more particularly,

to transformers which donot require lead-in I bushings for the high'voltage side.

Many efforts have been made to eliminate the ;lead-in'i1 1sulating bushings heretofore considered necessary for, the high-Voltage side of transformers for the reasons that such bushings are very expensive and'requlre 10] ficult to provide. -;For the purpose of eliminating such bushings, ithas been proposed to make the entire tank ofinsulating material. Heretofore, however, such insuisla'ting tanks were impractical because they were more expensive than the usual iron tanks with the lead-in bushings, or because offdifiicul'ties in the :construction of such tanks.

formed from insulating material.

A f urtherobject of the invention is to p'rovidela transformer having the portion of the side Walls of the tank a djacent the high voltage Winding foi'medfof insulating inaterial. i E v exterior Walls thereof partially formed bf I'iiisiilating material "which is coexten ive height of the high voltage Kohlywith the coils thereof. 7 l i r- Another object of the invention is taproa great amount of space which isgoft'en difone, of the objects of the fishermen--- tion, therefore, is to provide an improved ."vide a transformer Without lead-in bushings ride, in electric transformer apparatus,i means for producing an equal potential idrop 4 per unit of l'engt'h oyer the insulating casingsurrounding the primary winding,' to avoid is crass-sectional "view of an electric transformer embodying the present invention; and i I Figs. 2 to 5 are similar Views, showing varlo us mod fications of the invention.

by characters of reference, the reference numeral 1.0 indicates the bottom portion of Referring more specifically to the drawingv a tank which may be made. of iron or any other suitable material and Which is provided at its upper edge with a groove 11,

the purpose of Which yill'hereinafter appear. A cylinder 12, of insulating material having "suitable mechanical characteristics and of' s ub's tantially the same internal dimensions as bottom 10, is placed in groove 11' in such manner as to form a continuation'fof the bottom portion 10. A top portion 13, provided with a groove l i alo'ng the loweredgethereof for engagement Withinsulating cylinder 12, completes the tank which is closed by a suitablecfoyer 16. The joints or connections between cylinder 12 and the cylinder portions 10 and 13 are sealed tight in any suitable manner to prevent leakage of 011 or other insulating medium Withwliich the tank might be filled.

The tank is soproporti'oned'that cylinder 12 fclosely'surroun'ds the internal structure of the transformer, to be hereinafter described, for the purpose of vproducing a similar [potential drop perunit of length over the EEK- V l I 1 t l v V 'terio'r surface of the'cylinderinthe direction further object .ofthe invention isbto provide a transformer structure hayin'g'the of the longitudinal axis therethrough.

A' plurality of insulating members 17erranged Within vand resting upon the tank bottomflO support a core 18. A secondary The leads of the primary Winding are connected directly to the bottom 10 as at "22 and to the top 13 as at 23 vWithout"the use ofany chinbersome and expensive insulating bushings. "fllerminals (not shown) for the high-Voltage Winding are securedto the tank top portion13' or the cover 16 and to'the tank botwm pcrtibn io at the pointsfound distant points along the longitudinal axis fitted on the frame 26 as above described most convenient when installing the transformer. The secondary winding connections are preferably brought out of the tank through the bottom portion 10 by means of small tubes of insulating material, as shown, sealed to the tank in a liquid tight manner.

hen the windings are concentrated on one leg of core 18, a plurality of split metallic potential-dividing rings 24 are arranged; aboutthe unwoundleg of the core at equithereof to secure equal potential drop over the entire length of the windings whereby flash-overs and creepages over the surfaces of cylinder 12 may be avoided. The potential dividing rings 24 may also be arranged to surround core 18 and windings 19 and 21, as shown in Fig. 2. The potential dividing rings 24 may be supported from the inner surface of the insulation 12 but are preferably embedded in grooves in a wooden frame 26 arranged about the unwound leg of the core 18 and held between the cover 16 and the bottom of the tank.

The use of potential-dividing rings 24 may be avoided by dividing the windings into two series-connected portions as shown in Fig. 3, in which the primary windings are indicated at 21, 21a and the secondary windings are indicated at 19, 19a. In this constr ction, the several portions of the windings are arranged alternately on the several legs of the core to provide for an equal potential division without the use of rings 24.

The primary and secondary windings may also be connected as shown in Fig. 4, in which primary portions 21, 21a and secondary windings 19, 19a are connected in parallel and are arranged in different directions around the core. h

The low voltage winding may also be arranged on one end of the core, as shown in Fig. 5, rather than being arranged concentrically with the high voltage winding as shown and previously described. In such modified form of the invention, a compensating winding, divided into two portions 27 and 27a, is arranged adjacent both the high voltage winding 21 and the low voltage winding 19 which is arranged in spaced relation on the core 18 beside the high voltagewinding 21. The use and purposes of the compensating winding, 27a will be well understood by those skilled in the art. The potential dividing rings 24 are arranged and and are each connected with the coil forming the high-voltage winding for the purpose of obtaining a gradual potential drop from the supply to the ground potential. In this case the center of the high-voltage winding may be connected either directly or by means of a potential-dividing ring with the active iron core.

From the foregoing it will be seen that eliminated. The invention is therefore not restricted to transformers of any particular size nor even to transformers but may be used for other electrical apparatus ordinarily requiring lead-in bushings.

Although but a few embodiments of the invention have been illustrated and described, it will be understood that various other embodiments are possible, and that various changes may be made without departing from the spirit of the invention or the scope of the claims.

The invention claimed is:

1. In a tank for electrical apparatus, a metallic member forming the bottom of the tank, a member formed of insulating material and forming an extension of said tank bottom, a metallic member forming an extension of said insulating member, and a top member forming a cover for the tank.

2. In a tank for electrical apparatus, a dished metallic member forming a bottom portion for the tank, an annular member forming a top portion for the tank, a cylindrical member of insulating material joining said bottom and said top tank portions, and a plate-like member forming a cover for the tank.

3. In an electric transformer, a metallic member forming a tank bottom portion, a metallic member forming atank upper portion, an insulating member separating said bottom and said top tank portions, a high voltage winding arranged within the tank, said high voltage winding being substantially the same height as said insulating member, and a low Voltage winding arranged in inductive relation to said high voltage winding.

4. In an electric transformer, a metallic member forming a tank bottom portion, a metallic member formin a tank upper portion, an insulating mem ber separating said bottom and said top portions, a core arranged within the tank, a low voltage winding arranged on said core, and a high voltage winding arranged in inductive relation adjacent said low voltage windin 5. In an electric transformer, a metallic member forming a tank bottom portion, a

metallic member forming a tank upper portion, an insulating member joining said bottom and said top portions, a core arranged within the tank, insulating members supporting said core from said bottom por tion, a high voltage winding arranged on said core and a low voltage winding arranged n inductive relation 'ad acent said high voltage winding.

6'. In an electric transformer, a metallic member forming a tank bottom portion, a metallic member forming a tank upper portion, an insulating member separating said bottom and said top'portions, windings arranged in inductive relation Within the tank, and means for securing uniform potential drop over said windings arranged adjacent thereto.

7. In an electric transformer, a metallic member forminga tank bottom portion, a metalhc memberforming' a tank upper portion, an lnsulating member separatlng sald bottom and said top portions,a high Voltage winding arranged within the tank, the

terminals of said winding being connected with said top andsaid bottom portions of 

